High-pressure fuel supply pump including an electromagnetically driven intake valve

ABSTRACT

A high-pressure fuel supply pump including an electromagnetically driven intake valve is configured such that a pressure equalizing hole is provided in the valve stopper positioned between the valve and a pressurizing chamber. The pressure equalization hole connects a spring storage space, provided between a valve and a valve stopper, with a surrounding fluid passage. The high-pressure fuel supply pump is further configured such that an opening of the pressure equalizing hole at the spring storage chamber side is open at a position at the inner side of a diameter of the spring. Since the pressure in the pressurizing chamber can be introduced into the inner side of the spring without traversing the spring, the unstable behavior of the spring or the valve due to the introduced pressure eliminated. Since the force applied to the valve when the valve closes is stabilized, the closing timing of the valve is stable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. Ser. No. 14/368,041, filedJun. 23, 2014, which is the National Phase of PCT/JP2012/080665, filedNov. 28, 2012, which claims priority to Japanese Application No.2012-009538, filed Jan. 20, 2012, the disclosures of all of which arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a high-pressure fuel supply pumpincluding an electromagnetically driven intake valve, and particularlyto a high-pressure fuel supply pump where an electromagnetically drivenintake valve is configured from a valve of outwardly opening type whichhas a valve element at a pressurizing chamber side of a valve seat.

BACKGROUND ART

A conventional high-pressure fuel supply pump like the one describedabove is configured in the following manner as disclosed, for example,in Patent Document 1 and Patent Document 2. In particular, a valve isformed from a tubular member and is disposed at a pressurizing chamberside with respect to a valve seat (at the downstream side of the valveseat). A valve stopper is provided between the pressurizing chamber andthe valve, the valve stopper restricting the open position of the valve.A spring is located between the stopper and the valve, the springbiasing the valve ire the closing direction. A space housing a springtherein is formed between the valve and the valve stopper when such aconfiguration as described above is adopted. The space, an enclosedspace sealed off from surrounding fluid, has an influence on theresponsiveness of the valve. A communication path having the enclosedspace connected to a surrounding fluid passage is therefore provided.

PRIOR ART LITERATURE Patent Document

Patent Document 1: JP-2009-203987-A

Patent Document 2: JP-2006-291838-A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

An intake valve of a high-pressure pump, however, has fuel with agreatly high flow rate flowing around a very light valve in oppositedirections at times of intake and spilling. The valve of the intakevalve violently acts not only in forward and backward directions butalso in leftward and rightward or circumferential directions in the flowof fuel accordingly. In order to introduce the fuel pressure around thevalve into the enclosed space in such surrounding conditions asdescribed above, the surrounding fuel pressure has been introduced froma transverse direction of the valve across the spring in theconventional technologies. The valve of a light weight repeatedunpredictable unstable movements, leading to the intense discharge flowrate variation of the fuel. As a result, the pressure variation of acommon rail where the pump of the prior art is used is found out to beas great as in FIG. 7A in measurements. This variation had a negativeeffect on the fuel injection of the injector.

It is an object of the present invention to keep the movement of a valvesteady so as to stabilize the discharge flow rate of fuel against anunintended variation of fuel as a consequence and thereby to reduce thepressure variation of a common rail.

Means for Solving the Problems

In order to achieve the object described above, the present inventionoffers a pressure equalizing hole which connects a spring storage space,provided between a valve and a valve stopper, to a surrounding fluidpassage, the hole being provided in the valve stopper located betweenthe valve and a pressurizing chamber. The pressure equalizing hole isconfigured to have an opening thereof on a side of the spring storagespace, the opening being located on an inner side of a diameter of thespring

The pressure equalizing hole is preferably provided such that a centeraxial line thereof does not cross with the spring at the inner side ofthe spring.

The pressure equalizing hole preferably is a straight through-holeextending along the center axial line of the spring.

Preferably the valve stopper has a valve guide and the pressureequalizing hole extends through the valve guide.

The pressure equalizing hole is preferably open to the spring storagechamber beyond the position of a valve seat.

The pressure equalizing hole is preferably positioned on a center axialline of the valve.

The pressure equalizing hole is preferably positioned on a center axialline of a fuel introduction hole.

The pressure equalizing hole is preferably positioned on a center axialline of a plunger rod.

Effect of the Invention

The pressure in the pressurizing chamber can be introduced into theinner side of the spring without traversing the spring according to thepresent invention having the configuration described above. An unstablebehavior of the spring or the valve by the introduced pressure can beeliminated. Since the force applied to the valve when the valve closesis stabilized, the closing timing of the valve can be stable. As aresult, an unintended variation of the discharge amount is less likelyto occur.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a general vertical sectional view of a high-pressure fuelsupply pump which includes an electromagnetically driven intake valveaccording to a first embodiment in which the present invention iscarried out.

FIG. 2 is a system block diagram depicting an example of a fuel supplysystem which uses the high-pressure fuel supply pump in which thepresent invention is carried out.

FIG. 3(A) is an enlarged sectional view of an electromagnetically drivenintake valve according to the first embodiment in which the presentinvention is carried out and illustrates a state of the intake valve atthe time of opening (at times of fuel intake and spilling).

FIG. 3(B) is a view as seen in a direction indicated with an arrow markP in FIG. 3(A) illustrating a relation between a stopper and a valve ofthe electromagnetically driven intake valve according to the firstembodiment in which the present invention is carried out.

FIG. 3(C) is a view as seen in the direction indicated with the arrowmark P in FIG. 3(A) of the valve of the electromagnetically drivenintake valve according to the first embodiment in which the presentinvention is carried out.

FIG. 4(A) is an enlarged sectional view of the electromagneticallydriven intake valve according to the first embodiment in which thepresent invention is carried out and illustrates a state of the intakevalve in a state at the time of fuel discharge (upon valve closing).

FIG. 4(B) is an enlarged sectional view of the electromagneticallydriven intake valve according to the first embodiment in which thepresent invention is carried out and illustrates a state of the intakevalve in a state at the time of fuel discharge (at times of fuel intakeand spilling).

FIG. 5(A) is a sectional view depicting an electromagnetically drivenintake valve according to a second embodiment in which the presentinvention is carried out.

5(B) is a view as seen in the direction indicated with an arrow mark Pin FIG. 5(A) depicting a valve stopper of the electromagnetically drivenintake valve according to the second embodiment in which the presentinvention is carried out.

FIG. 6(A) is a sectional view depicting an electromagnetically drivenintake valve according to a third embodiment in which the presentinvention is carried out.

FIG. 6(B) is a view as seen in the direction indicated with an arrowmark P in FIG. 6(A) depicting a valve stopper of the electromagneticallydriven intake valve according to the third embodiment in which thepresent invention is carried out.

FIG. 7(A) is a graph illustrating a pressure variation of a conventionalcommon rail.

FIG. 7(B) is a graph illustrating a pressure variation of a common railwhere a high-pressure fuel supply pump in which the present invention iscarried out is used.

MODE FOR CARRYING OUT INVENTION

Embodiments of the present invention will be described with reference tothe drawings in the following.

First Embodiment

A first embodiment of a high-pressure fuel supply pump in which thepresent invention is carried out is described with reference to FIGS. 1to 4. Those reference numerals used in the following description but notin FIG. 1 cannot be applied in FIG. 1 to the details. The numbersinstead are applied in enlarged views later described.

A pump housing 1 is provided with a recessed portion 12A that forms abottomed tubular space open at one end of the tubular, the recessedportion 12A having A cylinder 20 inserted into the portion from the openend side. The space between an outer circumference of the cylinder 20and the pump housing 1 is sealed with a pressure contacting portion 20A.A piston plunger 2 is slidably fitted in the cylinder 20, andconsequently, an inner circumferential face of the cylinder 20 and anouter circumferential face of the piston plunger 2 are sealedtherebetween with fuel which enters between the slidably fitting facesof them. As a result, a pressurizing chamber 12 is defined between a tipend of the piston plunger 2 on the one hand and an inner wall face ofthe recessed portion 12A and an outer circumferential face of thecylinder 20 on the other.

A tubular hole 200H is formed so as to extend from a peripheral wall ofthe pump housing 1 toward the pressurizing chamber 12. An intake valveunit of an electromagnetically driving mechanism unit EMD and a part ofan electromagnetically driven intake valve mechanism 200 are inserted inthe tubular hole 200H. A joining face 200R between an outer peripheralface of the electromagnetically driven intake valve mechanism 200 andthe tubular hole 200H is joined to a gasket 300 to seal the inside ofthe pump housing 1 from the atmosphere. The tubular hole 200H sealed bythe attachment of electromagnetically driven intake valve mechanism 200functions as a low pressure fuel chamber 10 a.

At a position opposed to the tubular hole 200H across the pressurizingchamber 12, a tubular hole 60H is provided so as to extend from aperipheral wall of the pump housing 1 toward the pressurizing chamber12. A discharge valve unit 60 is mounted in the tubular hole 60H. Thedischarge valve unit 60 includes a valve seat member 61B which has avalve seat 61 formed at a tip end thereof and includes a through hole11A provided at the center thereof, the through hole 11A serving as adischarge passage. A valve holder 62 is secured to an outer periphery ofthe valve seat member 61B and surrounds the outer circumference of thevalve seat member 61B at the valve seat 61 side. A valve 63 and abiasing spring 64 are provided in the valve holder 62, and the biasingspring 64 biases the valve 63 in a direction to press the valve 63toward the valve seat 61. At an opening of the tubular hole 60H at theopposite side to the pressurizing chamber, a discharge joint 11 isprovided which is fixed to the pump housing 1 by means of a fasteningscrew.

The electromagnetically driven intake valve mechanism 200 includes anelectromagnetically driven plunger rod 201. A valve 203 is provided at atip end of the plunger rod 201 and opposed to a valve seat 214S formedon a valve housing 214. The valve housing 214 is provided at an endportion of electromagnetically driven intake valve mechanism 200.

A plunger rod biasing spring 202 is provided at the other end of theplunger rod 201 and biases the plunger rod in a direction in which thevalve 203 moves farther away from the valve seat 214S. A valve stopperS0 is fixed to an inner peripheral portion of a tip end of the valvehousing 214. The valve 203 is reciprocatably held between the valve seat214S and the valve stopper S0. A valve biasing spring S4 is disposedbetween the valve 203 and the valve stopper S0, the valve 203 beingurged by the valve biasing spring S4 in a direction in which the valve203 moves farther away from the valve stopper S0.

Although the valve 203 and the tip end of the plunger rod 201 are urgedin the opposite directions to each other by means of the individualsprings, since the plunger rod biasing spring 202 has a stronger spring,the plunger rod 201 pushes the valve 203 in a direction (rightwarddirection in FIG. 1) in which the valve 203 moves farther away from thevalve seat 214S against the force by the valve biasing spring S4. As aresult, the valve 203 is pressed toward the valve stopper S0.

Therefore, when the electromagnetically driven intake valve mechanism200 is in a power OFF state (when an electromagnetic coil 204 is notenergized), the valve 203 is urged in its opening direction by theplunger rod biasing spring 202 through the plunger rod 201. When theelectromagnetically driven intake valve mechanism 200 is in a power OFFstate, the plunger rod 201 and the valve 203 are maintained at theiropening position as depicted in FIGS. 1, 2 and 3(A) (detailedconfiguration is hereinafter described).

As depicted in FIG. 2, fuel is introduced to an intake joint 10 as afuel feed port of the pump housing 1 from a fuel tank 50 with the use ofa low pressure pump 51.

A plurality of injectors 54 and a pressure sensor 56 are mounted on acommon rail 53. The injectors 54 are mounted in accordance with thenumber of cylinders of the engine and inject high-pressure fuel fed tothe common rail 53 into the cylinders in response to a signal of anengine controlling unit (ECU) 600. A relief valve mechanism (not shown)built in the pump housing 1 opens when the pressure in the common rail53 exceeds a predetermined value to return the excessive high-pressurefuel to the upstream side of the discharge valve unit 60.

A lifter 3 provided at a lower end of the piston plunger 2 is subjectedto pressure wielding to a cam 7 by means of a spring 4. The pistonplunger 2 is slidably held in the cylinder 20 and is made to reciprocateby the cam 7 so as to change the volume of the pressurizing chamber 12.The cam 7 is rotated by an engine camshaft or the like. The cylinder 20is held at an outer circumference of a lower end portion thereof by acylinder holder 21. The cylinder 20 is subjected to the pressurewielding to the pump housing 1 at the pressure contacting portion 20A asa result of the cylinder holder 21 fixed to the pump housing 1.

A plunger seal 5 mounted on the cylinder holder 21 seals an outercircumference of a small diameter portion 2A formed at a lower endportion side of the piston plunger 2. An assembly of the cylinder 20 andthe piston plunger 2 is inserted in the pressurizing chamber, and a malethread portion 21A formed on an outer circumference of the cylinderholder 21 is screwed in a thread portion 1A of a male thread portionformed on an inner circumference of an open side end portion of therecessed portion 12A of the pressurizing chamber 12. After the cylinderholder 21 pushing the cylinder 20 to the pressurizing chamber side in astate in which a step portion 21D of the cylinder holder 21 is locked toa circumferential edge of a pressuring chamber side end portion of thecylinder 20, the pressure contacting portion 20A is pressed toward thepump housing 1 to form the seal portion as a consequence of metalcontact.

An O-snap ring 21B seals an area between an inner circumferential faceof an attachment hole EH formed in an engine block ENB and an outercircumferential face of the cylinder holder 21. An O-snap ring 21C sealsan area between an inner circumferential face of a pressurizing chamberside end portion of the recessed portion 12A of the pump housing 1 andan outer circumferential face of the cylinder holder 21 at a position ofthe side opposite to the pressurizing chamber side of the thread portion21A (1A).

The pump is screwed at a flange (its details are omitted) of the pumphousing 1 to the engine block. The pump is consequently fixed to theengine block.

A damper chamber 10 b is formed in the midway of a passage from theintake joint 10 to the low pressure fuel chamber 10 a. A two-ply metaldiaphragm type damper 80 is stored in the damper chamber 10 b in such astate that the two-ply metal diaphragm type damper 80 is sandwichedbetween a damper holder 30 and a damper cover 40. The two-ply metaldiaphragm type damper 80 has a pair of upper and lower metal diaphragms80A and 80B, which are butted with each other and welded at outerperipheral portions of the butted over an overall circumference to sealthe inside of the two-ply metal diaphragm type damper 80.

Inert gas such as argon gas is enclosed in a hollow formed by the metaldiaphragms 80A and 80B. The volume of the hollow varies in response to achange of the external pressure, the variation in turn leading topulsation attenuation function.

In particular, a step portion is formed on the inner circumference ofthe damper cover 40, and an annular groove is provided on the stepportion. The two-ply metal diaphragm type damper 80 is disposed suchthat its outer circumference welded portion fits completely in thegroove, so that external force may not be transmitted from thecircumjacent wall face to the two-ply metal diaphragm type damper 80.The two-ply metal diaphragm type damper 80 is further provided in such amanner that a portion of the face at one side of the two-ply metaldiaphragm type damper 80 (face at the side to which the intake joint 10of the damper cover is attached) which is at the inner side with respectto the outer circumferential welded portion may be held by the stepportion. The damper holder 30 is a bottomless cup-shaped member (memberwhich has a hole perforated at the center thereof and has, around thehole, a curved face with a cross section that is curved to the innerside). The damper holder 30 is force-fitted at an outer circumferencethereof in the inner circumferential face of the damper cover 40. An endface portion of the curved portion abuts, over an overall circumferencethereof, an annular face at the inner side with respect to the weldedportion of the outer periphery of the two-ply metal diaphragm typedamper 80. In a state in which the flange portion of the two-ply metaldiaphragm type damper 80 is sandwiched between the abutment and theabove-described step portion, the two-ply metal diaphragm type damper 80is formed as one assembly (unit) together with the damper holder 30 andthe damper cover 40. Thus, the damper chamber 10 b is formed as a resultof the pump housing 1 the damper cover 40 joined together with the useof screws. The intake joint 10 is configured perpendicularly to acentral portion of an upper face of the damper cover 40 by way pfintegral molding in the present embodiment. The intake joint 10therefore assumes the same posture at any position in the direction ofrotation even if the thread portion formed on the outer circumference ofthe damper cover 40 is screwed with the thread portion formed on aninner wall of the pump housing 1. The screwed position of the dampercover is not restrained, and the assembling properties of the dampercover 40 are improved.

A fuel passage 80U is provided between the diaphragm 80A at one side ofthe two-ply metal diaphragm type damper 80 and the damper cover 40. Thefuel passage 80U is connected to the damper chamber 10 b (fuel passagewhich the diaphragm 80B at the other side of the two-ply metal diaphragmtype damper 80 faces) as a fuel passage through a groove passage 80Cprovided on the inner peripheral wall of the damper cover 40. The damperchamber 10 b is made to communicate with the low pressure fuel chamber10 a through a communication hole 10 c formed in the pump housing 1which is a part of a bottom wall of the damper chamber 10 b. Theelectromagnetically driven intake valve (valve 203) is located in thelow pressure fuel chamber 10 a. The fuel fed from the fuel tank 50 flowsfrom the intake joint 10 into the damper chamber 10 b and acts upon bothmetal diaphragms 80A and 80B of the two-ply metal diaphragm type damper80. Meanwhile, the fuel flows into the low pressure fuel chamber 10 aafter passing the communication hole 10 c.

A connecting portion between the small diameter portion 2A and a largediameter portion 2B of the piston plunger 2 is provided as a conicalface 2K, the large diameter portion 25 slidably fits in with thecylinder 20. A fuel auxiliary chamber 250 is formed between the plungerseal 5 and a lower end face of the cylinder 20 around the conical face.The fuel auxiliary chamber 250 captures fuel leaking from the slidablycontacting face between the cylinder 20 and the piston plunger 2. Anannular passage 21G is defined and formed between an innercircumferential face of the pump housing 1 and an outer circumferentialface of the cylinder 20. The annular passage 21G is connected at one endto the damper chamber 10 b by way of a vertical passage 250B formed inand extending through the pump housing 1. The annular passage 21G isconnected to the fuel auxiliary chamber 250 through a fuel passage 250Aformed in the cylinder holder 21. Thus, the damper chamber 10 b and thefuel auxiliary chamber 250 are made to communicate with each otherthrough the vertical passage 250B, annular passage 21G, and fuel passage250A.

When the piston plunger 2 moves upwardly and downwardly (moves back andforth), the volume of the fuel auxiliary chamber 250 changes since thetapered face 2K reciprocates in the fuel sub chamber. The fuel flowsfrom the damper chamber 10 b into the fuel auxiliary chamber 250 throughthe vertical passage 250B, annular passage 21G, and fuel passage 250Awhen the volume of the fuel auxiliary chamber 250 increases. The fuelflows from the fuel auxiliary chamber 250 into the damper chamber 10 bthrough the vertical passage 250B, annular passage 21G, and fuel passage250A when the volume of the fuel auxiliary chamber 250 decreases. If thepiston plunger 2 moves upwardly from the bottom dead center when thevalve 203 is in a state in which it is maintained at the open position(when the coil 204 is in a non-energized state), then the fuel takeninto the pressurizing chamber overflows (spills) from the valve 203 inan open state into the low pressure fuel chamber 10 a and then flowsinto the damper chamber 10 b through the communication hole 10 c. Thus,the fuel from the intake joint 10, the fuel from the fuel auxiliarychamber 250, the overflowing fuel from the pressurizing chamber 12 andthe fuel from a relief valve (not shown) merge into the damper chamber10 b. As a result, fuel pulsations that the fuels have merge in thedamper chamber 10 b is absorbed by the two-ply metal diaphragm typedamper 80.

A region surrounded by a broken line in FIG. 2 indicates the pump bodypart. A yoke 205 is provided at the inner circumference side of the coil204 formed annularly and serves also as a body of theelectromagnetically driving mechanism unit EMD. The yoke 205 has astationary core 206 and an anchor 207 stored in an inner peripherythereof such that the plunger rod biasing spring 202 is sandwichedbetween the stationary core 206 and the anchor 207.

As particularly depicted in FIG. 3(A), the yoke 205 in the presentembodiment is divided into a side yoke 205A and an upper yoke 205B whichare joined together through press fitting. The stationary core 206 isformed from divisional parts of an outer core 205A and an inner core206B which are joined together through press fitting. The anchor 207 isfixed to an end portion of the plunger rod 201 at the opposite side tothe valve side through welding and opposes to the inner core 206B with amagnetic gap GP in-between. The coil 204 is stored in the yoke 205, anda thread portion provided on an outer periphery of an open end portionof the side yoke 205A is screwed with and fastened to a thread portion1SR of the pump housing 1 to fix the side yoke 205A and the pump housing1 to each other. Through this fixing work, the open end portion of theside yoke 205A pushes a flange portion 206F formed on an outer peripheryof the outer core 206A toward the pump housing. Thereupon, the outercircumference of an open side end portion tubular portion 206G of theouter core 206A is inserted into an inner circumferential face of aguide hole 1GH of the pump housing 1. Further, an annular increaseddiameter portion 206GS formed as a step portion on the cuter peripheryof the open side end portion tubular portion 206G of the outer core 206Ais pressed toward an annular face portion 1GS formed on thecircumference at the open side of the guide hole 1GH of the pump housing1. At this time, a seal ring 206SR disposed between the annular faceportion 1GS formed on the outer periphery at the opening side of theguide hole 1GH of the pump housing 1 and the flange portion 206F formedon the outer periphery of the outer core 206A is compressed.Consequently, the space at the low pressure side including the space onthe inner circumferential portion of the stationary core 206 and the lowpressure fuel chamber 10 a is sealed from the atmosphere.

A closed magnetic path CMP formed around the coil 204 from the side yoke205A and upper yoke 205B, outer core 206A and inner core 206B and anchor207 such that the closed magnetic path CMP traverses the magnetic gapGP. A portion of the outer core 206A which faces the periphery of themagnetic gap GP is formed in a slight thickness (when it is viewed fromthe outer periphery, a groove is formed), and this grooved portion formsa magnetic throttle 206S (having a function of magnetic resistance) ofthe closed magnetic path CMP. Accordingly, those magnetic fluxes whichleak through the outer core 206A can be reduced, and those magnetsfluxes which pass the magnetic gap GP can be increased as a result.

As depicted in FIGS. 3(A) to 3(C), 4(A) and 4(B), a bearing portion 214Bis fixed through press fitting on the inner circumferential portion ofthe tubular portion 206G formed at an open side end portion of the outercore 206A. The bearing portion 214(B) is formed at one end of the valvehousing 214. The plunger rod 201 extends through the bearing 214(B) tothe low pressure fuel chamber 10 a in the valve housing 214. Meanwhile,the valve 203 is stored in a center hole 214C (which functions as a fuelfeed port) formed at the other end side of the valve housing 214. Thevalve 203 extends, at a left side end portion thereof in the figures,from the position of the valve seat 214S through the center hole 214C tothe low pressure fuel chamber 10 a. The valve seat 214S is formed at anend face portion of the valve housing 214 at the pressurizing chamber 12side. As a result, the tip end of the plunger rod 201 is opposed to aflat face portion 203F of the valve 203 in the low pressure fuel chamber10 a.

A through-hole 201H is formed at the center of the plunger rod 201. Thethrough-hole 201H made to communicate at one end thereof with a storagespace for the plunger rod biasing spring 202 formed between the innercore 206B and the anchor 207. The through-hole. 201H is connected at theother end to the low pressure fuel chamber 10 a in the inside of thevalve housing. When the electromagnetically driving mechanism unit EMDis energized and the anchor 207 of the electromagnetic valve mechanism200 is attracted to the inner core 206B of the stationary core 206 sothat the valve 203 is pressed toward the valve seat 214S to establish aclosed valve state, the tip end of the plunger rod 201 is spaced fromthe flat face portion 203F of the valve 203. At this time, the lowpressure fuel chamber 10 a and the storage space for the plunger rodbiasing spring 202 are made to communicate with each other by thethrough-hole 201H. As a result, the fuel in the storage space for theplunger rod biasing spring 202 is discharged to the low pressure fuelchamber through the through-hole 201H. Consequently, the movement of theanchor 207 and the plunger rod 201 is smoothened. Further, even if thetip end of the plunger rod 201 is formed as a flat face, the stickingphenomenon between the tip end face of the plunger rod 201 and the flatface portion 203F of the valve 203 can be eliminated, and the supplypower to the coil 204 of the electromagnetically driving apparatus EMDcan be reduced. Forming the plunger rod 201 hollow decreases the weightof the plunger rod 201 and the driving power for the same as well.

The valve stopper S0 is fixed to the valve housing 214 as a result ofpress fitting the inner circumferential face of a tubular portion S1{depicted in FIG. 3(A)} at an end portion thereof at the valve 203 sidewith an outer circumference of a pressurizing chamber side end portionouter peripheral face 214D of the valve housing 214. Further, the outercircumferential face of the tubular portion S1 {depicted in FIG. 3(A)}of the valve stopper S0 is press fitted in the inner circumference ofthe guide hole 1GH (diameter D4) of the pump housing 1. The valve 203 isreciprocatably mounted between the tip end portion of the plunger rod201 and the valve stopper S0 with the valve biasing spring S4 interposedin-between. The valve 203 is opposed at a face at its one side to thepressurizing chamber side end face (valve seat 214S) of the valvehousing 214 and has, on the other side face, an annular face portion203R which opposes to the valve stopper S0. The valve 203 has, at itscentral portion of the annular face portion 203R, a bottomed tubularportion extending to the tip end of the plunger rod 201. The bottomedtubular portion is configured from a cylindrical portion 203H and theflat face portion 203F provided at the bottom of the tubular portion.The cylindrical portion 203H is stored in the center hole 214C of thevalve housing 214 and projects to the inside of the low pressure fuelchamber 10 a. A tubular fuel introduction passage 10P is formed betweenthe outer circumference of the cylindrical portion 203H and the innercircumferential face of the center hole 214C of the valve housing 214.It is to be noted that a portion of the outer periphery indicated withslanting lines in FIG. 3(B) conveniently indicates a part of the pumphousing 1 as an annular portion. The valve housing 214 and the tubularportion S1 of the valve stopper S0 can be seen in regions of the cutoutsSn1 to Sn3.

The tip end of the plunger rod 201 is dimensioned so that it can abutthe surface of the flat face portion 203F of the end portion of thevalve 203 at the plunger rod side in the low pressure fuel chamber 10 a.However, the tip end of the plunger rod 201 is dimensioned so that, whenthe valve 203 is closed {state in FIG. 4(A)}, the tip end can betemporarily (within a certain period during energization of theelectromagnetic coil) away by a distance Δs from the valve 203. Fourfuel through-holes 214Q are provided in an equally spaced intervals fromeach other in a circumferential direction at a tubular portion of thevalve housing 214 between the bearing 214B and the center hole 214C ofthe valve housing 214. The four fuel through-holes 214Q is connected tothe inner side of the valve housing 214 and the low pressure fuelchamber 10 a at the outer side of the valve housing 214. The tubularfuel introduction passage 10P is formed between the outercircumferential face of the cylindrical portion 203H of the valve 203and the inner circumferential face of the center hole 214C of the valvehousing 214. The fuel introduction passage 10P is connected at its oneend to the low pressure fuel chamber 10 a and at the other end to anannular (disk-shaped) fuel passage 10S formed between the valve seat214S and the annular face portion 203R of the valve 203.

The valve stopper S0 has at its central portion a projection STprojecting to the bottomed tubular portion side of the valve 203, theprojection ST having a cylindrical face portion SG. The cylindrical faceportion SG functions as a guide portion for guiding the valve 203 duringa stroke in an axial direction. The valve biasing spring S4 is retainedbetween a valve side end face SH of the projection ST of the valvestopper S0 and the bottom face of the bottomed tubular portion of thevalve 203. If the valve 203 strokes the fully open position under theguidance of the cylindrical face portion SG of the valve stopper S0,then an annular projection 203S formed at a central portion of theannular face portion 203R of the valve 203 is brought into contact abottom face portion receiving face S2 (width HS2) of the valve stopperS0. At this time, an annular air gap SGP is formed around the annularprojection 203S. The annular air gap SGP provides an early leavingfunction of causing, when the valve 203 starts its movement to the valveclosing direction, pressure P4 of the fuel at the pressurizing chamberside to act upon the valve 203 so that the valve 203 rapidly leaves thevalve stopper S0.

The valve stopper S0 as depicted in FIG. 3(B) includes the three cutoutsSn1 to Sn3 formed at different positions spaced by a particular distancefrom each other. The cutouts Sn1 to Sn3 are configured in such a mannerthat the total passage sectional area is greater than that of theannular fuel passage 10S formed between the valve seat 214S and theannular face portion 203R of the valve 203. As a result, the cutouts Sn1to Sn3 do not provide passage resistance with the inflow of the fuelinto the pressurizing chamber or the spill of the fuel from thepressurizing chamber. The fuel thereby flows smoothly.

With reference to FIG. 3(C), the diameter D1 of the outercircumferential face of the valve 203 is configured to be slightlysmaller than the diameter D3 {refer to FIG. 3(B)} of the cutout portionsof the valve stopper S0. As a result, in a spilling state in which thefuel flows from the pressurizing chamber 12 into the damper chamber 10 bpast the intake joint 10 along a fuel flow R5 (FF) in FIGS. 3(A) and3(B), static and dynamic fluid forces of the fuel at the pressurizingchamber 12 side indicated with an arrow mark P4 are less likely to actupon the annular face portion 203R of the valve 203.

A pressure equalizing hole S5 and a large diameter hole S6 are providedin the projection ST of the valve stopper S0 disposed at the inner sideof the valve annular projection 203S. The pressure equalizing hole S5 isconnected to the pressurizing chamber and a storage space SP for thevalve biasing spring S4 provided between the valve 203 and the valvestopper S0. The large diameter hole S6 has a diameter greater than thepressure equalizing hole S5.

The pressure in the storage space SP is kept constant since the fuel isaccordingly supplied into the spring storage space SP, in which thevalve biasing spring S4 is stored, through the pressure equalizing holeS5 when the valve 203 closes. The force applied to the valve 203 whenthe valve 203 closes thereby becomes stable, which in turn can stabilizethe closing timing of the valve 203.

The pressure equalizing hole S5 is disposed on the center axis of all ofthe valve stopper S0, projection ST, valve 203, annular projection 203S,spring storage space SP, valve biasing spring S4, valve seat center hole214C, plunger rod 201 and tubular fuel introduction passage 10P.

Consequently, when the fuel is supplied into the storage space SPthrough the pressure equalizing hole S5 at the time the valve 203closing, the pressure of the fuel does not act upon the spring.Therefore, such a situation will not occur that the spring vibrates orthe spring is partially deformed by an action of the fuel entering thestorage space SP. Since the force of the spring is only approximately300 grams, if the fuel hits upon the spring when it enters from thepressure equalizing hole S5, then the spring is deformed readily by theflowing force or the pressure of the fuel. In an extreme case the springvibrates to make the valve 203 tilted or immobile. The fuel does notcontact the spring and the fuel pressure is introduced uniformly in acircumferential direction of the valve 203 from the pressurizing chamber12 side into the storage space SP in the present embodiment. The closingtiming of the valve 203 can be stabilized accordingly. In addition,since the pressure equalizing hole S5 is provided at the center of thevalve stopper S0, there is no necessity to assemble the valve stopper S0at the time of assembly of the valve stopper S0 while the pressureequalizing hole S5 is suitably positioned for every product. Theassembly will not be complicated.

The pressure equalizing hole S5 preferably has a small diameter. This isintended to prevent the intake valve (valve 203) from being closed at anunexpected timing by a fluid pressure generated due to spilling fuelbecause the static or dynamic fluid force of the fuel at thepressurizing chamber 12 side indicated with an arrow mark P is lesslikely to act. Although it is preferable to prevent a dynamic componentfrom entering the spring storage space SF but allow only a necessarystatic pressure to be introduced into the storage space SP, it is notdenied for the fuel to flow into the storage space SP. An amount of thefuel is permissible as long as it is smoothly introduced into anddischarged from the storage space SF in response to opening and closingof the valve 203.

Not only one pressure equalizing hole S5 may be provided, but aplurality of pressure equalizing holes S5 may be formed in an equallyspaced intervals from each other around the center axis of the spring.In this case, the pressure equalizing holes S5 preferably should beconfigured in such a manner that the fuel introduced from the pressureequalizing holes S5 is introduced in parallel to the center axial lineof the spring. The fuel alternatively can be introduced toward thecenter axis of the valve biasing spring S4 toward the rear face of theflat face portion 203F of the valve 203, so that pressure action axes ofthe fuel (center axial lines of the pressure equalizing holes S5) maynot directly hit the spring. It should be taken into consideration thatthe pressure of the fuel introduced from the pressure equalizing holesS5 may act equally in a circumferential direction as seen from the valve203. According to an optimum embodiment, the valve 203 may be configuredsuch that the center axial line thereof overlaps with the center axialline of the valve biasing spring S4. Further, the valve guide SG formedfrom the outer circumference of the projection ST provided on the valvestopper S0 may be configured so that it guides the valve 203 so that thecenter axial line overlaps the center axial line of the valve 203.Further, the pressure equalizing holes S5 is preferably configured sothat the center axial lines overlap the center axial line of the valveguide SG. Moreover, if the tip end of the pressure equalizing hole S5 isopen to the position of the flat face portion 203F side of the valve 203beyond the position of the valve seat 214S at this time, then anautomatic centering action like that of a balance toy can be expected ina state where the valve 203 is supported on a pressure line of pressurefluid of the fuel introduced from the pressure equalizing holes S5.

The valve 203 in the embodiment has a weight of several milligrams, adiameter of 10.8 (mm) at the annular face portion 203R {D1 in FIG. 3(C)}and a diameter of 6.1 (mm) at an outer circumference of the cylindricalportion 203H, and an axial length of 7.4 (mm) from a stopper side endface of the annular projection 203S to the plunger rod 201 side end faceof the flat face portion 203F thereof. If the passage sectional area ofthe fuel introduction passage 10P is calculated, then it will be2.1*fifth power of 10 (square meters) since the inner diameter of theguide hole 1GH is 8.0 (mm) and the outer diameter of the tubular portionof the valve is 6.1 mm. If it is assumed that the speed of rotation ofthe engine is 6,000 rpm, then the period of rotation of the cam is 50(Hz) and the speed of rotation of the cam is 314.2 (rad/sec). From thatinformation, if the cam is a four-leaf cam, then the maximum speed ofthe piston plunger 2 at times of spilling and intake is approximately7.6 (rad/mm), namely, 2,383 (mm/sec). The maximum flow velocity isapproximately 8.9 (m/sec) and the flow rate at this time is 1.9*fourthpower of 10 (cubic meters). If the cam is a three-leaf cam, then themaximum speed of the piston plunger 2 at times of spilling and suctionis approximately 8.1 (rad/mm), namely, 2,553 (m/second) The maximum flowvelocity is approximately 9.5 (m/sec) and the flow rate at this time is1.9*fourth power of 10 (cubic meters). The force of the valve biasingspring S4 is approximately 3 (Nm).

In this manner, fuel of a greatly high flow rate flows around the quitelight valve 203 in the opposite directions at times of suction andspilling. The valve 203 acts violently not only in the backward andforward directions but also in the leftward and rightwardcircumferential directions in the fluid for this reason, which hasresulted in the great variation in discharge flow rate of the fuel. Thepressure variation was found out to be great as depicted in FIG. 7A inthe measurement of the pressure variation at the common rail at the timea prior art pump is used. In particular, when it was tried to controlthe pressure to 20 Mpa, a great pressure variation occurred between 23Mpa in the maximum-18 Mpa in the minimum. In contrast, the pressurevariation at the common rail using the high pressure fuel supply pump towhich the present invention is applied was measured next. And thepressure variation when it was tried to control the pressure to 20 Mpawas suppressed successfully to minute variation as depicted in FIG. 7B.

Operation of the first embodiment will be described with reference toFIGS. 1, 2, 3(A), 3B, 4(A), and 4(B).

Fuel Suction State

A fuel intake state will now be described with reference to FIGS. 1, 2,3(A), and 4(B). In an intake operation in which the piston plunger 2moves downwardly in a direction indicated with an arrow mark Q2 from thetop dead center position indicated with a broken line in FIG. 2, thecoil 204 is in a non-energized state. Biasing force SP1 of the plungerrod biasing spring 202 biases the plunger rod 201 toward the valve 203as indicated with an arrow mark. Meanwhile, biasing force SP2 of thevalve biasing spring S4 biases the valve 203 in a direction indicatedwith an arrow mark. Since the biasing force SP1 of the plunger rodbiasing spring 202 is set higher than the biasing force SP2 of the valvebiasing spring S4, the biasing force of the springs at this time biasesthe valve 203 in the valve opening direction. The valve 203 is subjectedto force in the valve opening direction as a consequence of a pressuredifference between a static pressure P1 of the fuel acting upon theouter surface of the valve 203 represented by the flat face portion 203Fof the valve 203 positioned in the low pressure fuel chamber 10 a and apressure P12 of the fuel in the pressurizing chamber. Further, fluidfriction force P2 generated between the fuel flow which flows into thepressurizing chamber 12 along an arrow mark R4 through the fuelintroduction passage 10P and the circumferential face of the cylindricalportion 203H of the valve 203 biases the valve 203 in the valve openingdirection. Furthermore, a dynamic pressure P3 of the fuel flow whichpasses the fuel passage 10S formed between the valve housing 214 and theannular face portion 203R of the valve 203 acts upon the annular faceportion 203R of the valve 203 to bias the valve 203 in the valve openingdirection. The valve 203 whose weight is several milligrams is openedquickly due to the biasing forces once the piston plunger 2 starts tomove downwardly. The valve 203 thereafter strokes until it collides withthe valve stopper S0.

The valve housing 214 is formed on the outer side with respect to thecylindrical portion 203H of the valve 203 and the fuel introductionpassage 10P in a diametrical direction. Consequently, at is possible toenlarge the area upon which the static pressure P1, fluid friction forceP2, and dynamic pressure P3 P2 act and to enhance the opening speed ofthe valve 203. At this time, since the peripheral region of the plungerrod 201 and the anchor 207 is filled with resident fuel, and frictionforce of the fuel with the bearing portion 214B acts, the stroke of theplunger rod 201 and the anchor 207 in the rightward direction in thefigures delays a little from the opening speed of the valve 203. As aresult, a small gap is generated between the tip end face of the plungerrod 201 and the flat face portion 203F of the valve 203. Consequently,the valve opening force applied from the plunger rod 201 drops for amoment. However, since the static pressure P1 of the fuel in the lowpressure fuel chamber 10 a acts upon the gap without a delay, the dropof the valve opening force applied from the plunger rod 201 (plunger rodbiasing spring 202) is compensated for by the fluid force in the openingdirection of the valve 203. Thus, at the time of opening of the valve203, the static pressure and the dynamic pressure of the fluid act uponthe overall surface of the valve 203 at the low pressure fuel chamber 10a side, and consequently, the valve opening speed is accelerated.

At the time of opening of the valve 203, the inner circumferential faceof the cylindrical portion 203H of the valve 203 is guided by the valveguide formed from the cylindrical face portion SG of the projection STof the valve stopper S0. The valve 203 smoothly strokes without beingdisplaced in a diametrical direction. The cylindrical face portion SGwhich forms the valve guide is formed across the upstream side and thedownstream side across the face on which the valve seat 214S is formed.Therefore, not only the stroke of the valve 203 can be supported, butalso the dead space at the inner periphery side of the valve 203 can beutilized effectively. The dimension of the intake valve unit in theaxial direction can be reduced accordingly. Further, the valve biasingspring S4 is installed between the valve side end face SH of the valvestopper S0 and the valve stopper S0 side bottom face portion of the flatface portion 203F of the valve 203. While the passage area of the fuelintroduction passage 10P formed between the opening 204P and thecylindrical portion 203H of the valve 203 can be assured sufficiently,the valve 203 and the valve biasing spring S4 can be disposed on theinner side of the opening 214P. Since the valve biasing spring S4 can bedisposed as a result of the dead space effectively utilized at the innerperiphery side of the valve 203 positioned on the inner side of theopening 214P which forms the fuel introduction passage 10P, thedimension of the intake valve unit in the axial direction can bereduced.

The valve 203 has a valve guide (SG) at its central portion and has theannular projection 203S which contacts with the receiving face S2 for anannular face portion S3 of the valve stopper S0 immediately on the outerperiphery of the valve guide (SG). Further, the valve seat 214S isformed at a position at the outer side in a diametrical direction withrespect to the annular projection 203S, and the annular air gap SGPextends to a further outer side in the radial direction. The largediameter hole S6 is formed from an inner circumferential face of thevalve housing at the outer side of the annular air gap SGP (at the outerperiphery side of the valve 203 and the valve stopper S0). Since thelarge diameter hole S6 is formed on the outer side in the diametricaldirection of the valve housing 214, there is an advantage that the largediameter hole S6 can be assured to be sufficiently large.

Further, the annular projection 203S which contacts with the receivingface S2 of the valve stopper S0 is provided at the inner side of thevalve housing 214 at the inner side of the annular air gap SGP.Therefore, in a valve closing movement hereinafter described, it ispossible to cause a fluid pressure P4 at the pressurizing chamber sideto act upon the annular air gap SGP rapidly so as to raise the valveclosing speed when the valve 203 is pressed toward the valve housing214.

Fuel Spilling State

A fuel spilling state will be described with reference to FIGS. 1, 2,3(A), and 4(B). The piston plunger 2 begins to move upwardly in thedirection of an arrow mark Q1 from the bottom dead center position.Thereupon, since the coil 204 is in a non-energized state, part of thefuel taken into the pressurizing chamber 12 is spilled (spilt) into thelow pressure fuel chamber 10 a through the cutouts Sn1 to Sn3, fuelpassage 10S, and fuel introduction passage 10P. When the flow of thefuel in the large diameter hole S6 changes over from the direction ofthe arrow mark R4 to the direction of the arrow mark R5, the flow of thefuel stops for a moment and the pressure in the annular air gap SGPrises. However, the plunger rod biasing spring 202 presses the valve 203toward the valve stopper S0 at this time. Rather, the valve 203 ispressed firmly toward the valve stopper S0 by means of the two types offluid pressure: the first one pressing the valve 203 toward the valvestopper S0 with the use of the dynamic pressure by the fuel flowing intothe low pressure fuel chamber 10 a of the valve housing 214; and thesecond one acting so as to attract the valve 203 and the valve stopperS0 to each other by means of the sucking effect of the fuel flow whichflows along the outer periphery of the annular air gap SGP.

After a moment at which the flow stream changes over to the R5direction, the fuel in the pressurizing chamber 12 flows into the lowpressure fuel chamber 10 a successively passing the large diameter holeS6, annular fuel passage 10S, and fuel introduction passage 10P. Here,the fuel flow path sectional area of the fuel passage 10S is set smallerthan that of the large diameter hole S6 and the fuel introductionpassage 10P. In other words, the fuel flow path sectional area is setsmallest at the annular fuel passage 10S. Therefore, pressure loss isgenerated at the annular fuel passage 10S and the pressure in thepressurizing chamber 12 begins to rise. However, the fluid pressure P4is received at the annular face of the valve stopper S0 at thepressurizing chamber side and is less likely to act upon the valve 203.Since the pressure equalizing hole S5 has a small diameter, the dynamicfluid force of the fuel at the pressurizing chamber 12 side indicatedwith the arrow mark P4 Less likely to act upon the valve 203.

In the spilling state, the fuel flows from the low pressure fuel chamber10 a into the damper chamber 10 b through the annular air gap SGP andthrough the four fuel through holes 214Q. Since the piston plunger 2moves upwardly and the volume of the fuel auxiliary chamber 250thereupon increases, part of the fuel is introduced from the damperchamber 10 b into the fuel auxiliary chamber 250 by means of a fuel flowin a down ward arrow mark direction of an arrow mark R8 through thevertical passage 250B, annular passage 21G, and fuel passage 250A. Thecold fuel is thus supplied into the fuel sub chamber, and the slidingregion between the piston plunger 2 and the cylinder 20 is cooledaccordingly.

Fuel Discharging State

A fuel discharging state will be described with reference to FIG. 4(A).If the coil 204 is energized in accordance with an instruction from theengine controlling apparatus ECU in the fuel spilling state describedabove, then a closed magnetic path CMP is created as depicted in FIG.3(A). When the closed magnetic path CMP is formed, magnetic attractiveforce is generated between opposing faces of the inner core 206B and theanchor 207 in the magnetic gap GP. This magnetic attractive forceovercomes the biasing force of the plunger rod biasing spring 202 toattract the anchor 207 and the plunger rod 201 fixed to the anchor 207toward the inner core 206B. At this time, the fuel in the magnetic gapGP and the storage chamber 206K for the plunger rod biasing spring 202passes through the through-hole 201H and the periphery of the anchor 207and is discharged from the fuel passage 214K to the low pressurepassage. Consequently, the anchor 207 and the plunger rod 201 aredisplaced to the inner core 206B side smoothly. Once the anchor 207 isbrought into contact the inner core 206B, the movement of the anchor 207and the plunger rod 201 stops.

Since the plunger rod 201 is attracted to the inner core 206B and thebiasing force which biases the valve 203 to the valve stopper S0 sidedisappears, the valve 203 is urged in a direction where it moves fartheraway from the valve stopper S0 due to the biasing force by the valvebiasing spring S4. The valve 203 then begins its movement. At this time,the pressure in the annular air gap SGP positioned at the outerperiphery side of the annular projection 203S becomes higher than thepressure at the low pressure fuel chamber 10 a side accompanied with thepressure rise in the pressurizing chamber 12 thereby to assist theclosing movement of the valve 203. The valve 203 is brought into contactthe valve housing 214 to establish a valve closed state. This state isillustrated in FIG. 4(A). As the piston plunger 2 consecutively movesupwardly, the volume of the pressurizing chamber 12 decreases and thepressure in the pressurizing chamber 12 increases. As a result, thevalve 63 of the discharge valve unit 60 moves away from the valve seat61 as depicted in FIGS. 1 and 2 after overcoming the force of thebiasing spring 64. The fuel is then discharged from the through hole 11Ain directions along arrow marks R6 and R7 through the discharge joint11.

In this manner, the annular air gap SGP exhibits an advantage ofassisting the closing movement of the valve 203. There was a problemthat the valve closing movement is not stabilized since the valvebiasing spring S4 itself exerts excessively little closing force of theintake valve.

Since the fuel is supplied into the storage space SP through thepressure equalizing hole S5 when the valve 203 is closed, the pressurein the storage space SP becomes constant, and the force applied when thevalve 203 is closed is stabilized. The closing timing of the valve 203can be stable as a result.

It is accordingly possible to reduce the dispersion of the valve closingtiming with the present invention while the responsiveness at times ofopening and closing of the valve is enhanced.

Second Embodiment

A second embodiment will be described with reference to FIGS. 5A and 5B.Those elements having like functions to those in the first embodimentare denoted by like reference numerals in FIGS. 5A and 5B. Anelectromagnetically driven intake valve of the second embodimentdepicted in FIGS. 5A and 5B is configured as a valve of the outwardlyopening type including a valve 203 at a pressurizing chamber 12 side ofa valve seat 214S. The valve 203 is disposed at a pressuring chamberside with respect to the valve seat 214S (at a downstream side of thevalve seat). A valve stopper S0 is disposed between the pressurizingchamber 12 and the valve 203 and restricts the opening position of thevalve 203. Through-holes SN1 to SN6 (corresponding to the cutouts Sn1 toSn3) are provided in the valve stopper S0 and form fuel passages at anouter side of the valve 203 in a circumferential direction. A tubularfuel introduction passage 10P is connected at its one end to a lowpressure fuel chamber 10 a and at the other end to an annular(disk-shaped) fuel passage 10S formed between the valve seat 214S and aflat face portion 203F of the valve 203. The through-holes SN1 to SN6configure passages for connecting the pressurizing chamber 12 and theannular (disk-shaped) fuel passage 10S with each other. A valve biasingspring S4 is provided between the valve stopper S0 and the valve 203 andbiases the valve 203 in its closing direction. A spring storage space SPis formed between the valve 203 and the valve stopper S0 and houses thevalve biasing spring S4 therein. A pressure equalizing hole S5 as acommunication passage for connecting the spring storage space SP and thepressurizing chamber 12 with each other is provided at the center of thevalve stopper S0.

Whenever the plunger in the pressurizing chamber 12 enters a compressionoperation and the coil is energized at a valve closing timing, theplunger rod 201 is pulled leftwardly in FIGS. 5A and 5B against theforce of the plunger rod biasing sprig 202. The left end of the plungerrod 201 then moves away from the flat face portion 203F of the valve203. The valve 203 is urged in the closing direction by means of thevalve biasing spring S4 at this time. The pressure in the pressurizingchamber is introduced into the inner side, particularly to the center,of the valve biasing spring S4 through the pressure equalizing hole S5without traversing the spring. The introduced pressure is distributeduniformly to the inner circumferential face of the valve 203 and assiststhe closing movement of the valve 203 without having a negativeinfluence on the closing movement the valve 203. When the compressionoperation ends and the piston plunger 2 enters an intake operation, thenthe valve 203 is pushed rightwardly in FIGS. 5(A) and 5(B) against theforce of the valve biasing spring S4 by means of the force of theplunger rod biasing spring 202 and the pressure difference across theannular (disk-shaped) fuel passage 10S. The valve 203 subsequentlyenters an open state. At this time, the fuel in the spring storage spaceSP is discharged from the pressure equalizing hole S5 due to themovement of the valve 203. While the outer circumferential face of thevalve 203 is guided by the inner circumferential face of the valvestopper S0 in the present embodiment, the function of the pressureequalizing hole S5 is fundamentally the same as that in the firstembodiment.

Third Embodiment

A third embodiment will be described with reference to FIGS. 6A and 6B.Those elements having like functions to those in the first embodimentare denoted by like reference numerals in FIGS. 6A and 6B. Anelectromagnetically driven intake valve of the third embodiment depictedin FIGS. 6A and 6B is configured from a valve of the outwardly openingtype including a valve 203 at a pressurizing chamber 12 side of a valveseat 214S. The valve 203 is disposed at a pressuring chamber side withrespect to the valve seat 214S (at a downstream side of the valve seat).A valve stopper S0 is provided between the pressurizing chamber 12 andthe valve 203 and restricts the open position of the valve 203.Through-holes SN1 to SN6 (corresponding to the cutouts Sn1 to Sn3 in thefirst embodiment and corresponding to the through-holes SN1 to SN6 inthe second embodiment) are provided so as to extend obliquely outwardlyfrom an end face of the valve stopper S0 the pressurizing chamber sidethrough the valve stopper S0. In the third embodiment, the valve stopperS0 is press-fitted and fixed at are outer circumference thereof with andto an inner circumference of a tip end of a valve housing 214. A guideSGV is provided on the outer circumference of the valve stopper S0 atthe valve 203 side such that it guides the inner circumferential face ofthe valve 203. A tubular fuel passage 12V is formed between the outerperiphery of the valve 203 and the inner periphery of the valve housing.A tubular fuel introduction passage 10P is connected at its one end tothe low pressure fuel chamber 10 a and at the other end to an annular(ring-shaped) fuel passage 10S formed between the valve seat 214S and anannular projecting face portion 203M Projecting from the flat faceportion 203F of the valve 203. The through-holes SN1 to SN6 configurepassages for connecting the pressurizing chamber 12 and the tubular fuelpassage 12V with each other, and the annular (ring-shaped) fuel passage10S is made to communicate with the tubular fuel passage 12V. A valvebiasing spring S4 is provided between the valve stopper S0 and the valve203 and biases the valve 203 in the closing direction. A spring storagespace SP is formed between the valve 203 and the valve stopper S0 andhouses the valve biasing spring S4 therein. A pressure equalizing holeS5 as a communication path for connecting the spring storage space SPand the pressurizing chamber 12 with each other is provided at thecenter of the valve stopper S0. A large diameter hole S6 having adiameter greater than that of the pressure equalizing hole S5 isprovided at the pressurizing chamber 12 side of the pressure equalizinghole S5. The pressure equalizing hole S5 extends from the bottom of thelarge diameter hole S6 to the spring storage space SP. To configure thepressure equalizing hole S5 from a hole of a different diameter in thismanner is the same as that in the case of the first embodiment. In thepresent embodiment, the valve housing 214 is press-fitted at an outerperiphery of its one end in the inner periphery of a guide hole 1GHprovided in the pump housing 1 and is fixed at the other end in theaxial direction by means of a C-snap ring CR locked to the pump housing1.

Whenever the plunger in the pressurizing chamber 12 enters a compressionoperation and the coil is energized at a valve closing timing, theplunger rod 201 is pulled leftwardly in FIG. 6(A) against the force of aspring not shown. The tip end of the plunger rod 201 then moves awayfrom the annular projecting face portion 203M. At this time, the valve203 is urged in the closing direction by means of the valve biasingspring S4. The pressure in the pressurizing chamber is introduced intothe inner side, especially to a central region, of the valve biasingspring S4 through the pressure equalizing hole S5 without traversing thevalve biasing spring S4. The pressure introduced in the spring storagespace SP is distributed uniformly to the inner circumferential face ofthe valve 203 and assists the closing movement of the valve 203 withouthaving a negative influence on the closing movement of the valve 203.After the compression operation ends and the piston plunger 2 enters anintake operation, the valve 203 is pushed rightwardly in FIGS. 6(A) and6(B) against the force of the valve biasing spring S4 by means of theforce of the spring (not shown) of the electromagnetically drivingapparatus and the pressure difference across the annular (ring-shaped)fuel passage 10S and enters an open state. At this time, the fuel in thespring storage space SP is discharged from the pressure equalizing holeS5 due to the movement of the valve 203. While the inner circumferentialface of the valve 203 is guided by the guide SGV formed on the outercircumference of the valve stopper S0 in the present embodiment, thefunction of the pressure equalizing hole S5 is basically the same asthat in the first embodiment.

REFERENCE NUMERALS

1 pump housing

2 piston plunger

3 lifter

4 spring

5 plunger seal

7 cam

10 intake joint

10 a low pressure fuel chamber

10 b damper chamber

10 p fuel introduction passage

10S annular fuel passage

11 discharge joint

12 pressurizing chamber

20 cylinder

21 cylinder holder

22 seal holder

30 damper holder

40 damper cover

50 fuel tank

51 low pressure pump

53 common rail

54 injector

56 pressure sensor

80 metal diaphragm damper (assembly)

200 electromagnetically driven intake valve mechanism

201 plunger rod

203 valve

203H cylindrical portion

214 valve housing

214P opening

214S valve seat

250 fuel auxiliary chamber

600 engine controlling unit (ECU)

EMD electromagnetically driving mechanism unit

S0 valve stopper

SG valve guide

The invention claimed is:
 1. A high pressure fuel pump comprising: apressurizing chamber provided in a pump housing, an intake valve openingand closing a fuel passage communicating a low pressure chamber and thepressurizing chamber, a valve stopper restricting an open position ofthe intake valve, and a spring biasing the intake valve in a valveclosing direction provided in a space between the intake valve and thevalve stopper, wherein the valve closing direction is an axial directionof the intake valve; wherein the valve stopper forms a passage forcommunicating the space with an outside of the space, and includes aguide portion for guiding opening and closing of the intake valve,wherein the intake valve comprises: a bottom portion in contact with thespring, and a cylindrical portion guided by the guide portion, and aninner peripheral surface of the cylindrical portion faces the spring, acontact portion in contact with the valve stopper in a full valveopening position, and a non-contact portion forming a gap between thevalve stopper and the intake valve in the full valve opening position,wherein the non-contact portion is located outwardly of the cylindricalportion in a radial direction of the intake valve.
 2. The high pressurefuel pump according to claim 1, wherein the inner peripheral surfaceguides a movement of the spring.
 3. The high pressure fuel pumpaccording to claim 1, wherein an inner surface of the bottom portion isformed in a flat shape.
 4. The high pressure fuel pump according toclaim 1, wherein the cylindrical portion has an annular portionextending radially outward of an outer diameter of the cylindricalportion.
 5. The high pressure fuel pump according to claim 1, whereinthe passage is configured such that the space is communicated with thepressurizing chamber in a close position of the intake valve, and anouter circumferential surface of the valve stopper is in contact with aninner circumferential surface of a hole in the pump housing.